4-Trifluoromethylphenylhydrazinomethylene-malononitriles

ABSTRACT

New N-phenylpyrazole derivatives of the formula: ##STR1## (wherein R 12  represents a chlorine atom, R 13  represents a hydrogen, fluorine or chlorine atom, R 14  represents a hydrogen or fluorine atom and R 15  represents a hydrogen, fluorine or chlorine atom, with the proviso that when R 14  represents a fluorine atom, R 15  represents a fluorine or chlorine atom, or R 12 , R 13  and R 15  each represents a fluorine atom and R 14  represents a hydrogen or fluorine atom) possess useful herbicidal properties.

This is a division of application Ser. No. 398,336 filed July 15, 1982,U.S. Pat. No. 4,504,740.

DESCRIPTION

This invention relates to N-phenylpyrazole derivatives, compositionscontaining them and their use as herbicides.

In J. Heter. Chem., 12 (1975), 1199-1205, P. L. Southwick and B. Dhawanhave described experiments for the preparation of4,6-diaminopyrazolo[3,4-d]pyrimidines in the expectation that suchpyrimidine derivatives would have useful pharmacological properties.They employed as starting materials 1-phenyl-5-amino-4-cyanopyrazoles ofthe general formula: ##STR2## wherein R represents inter alia a hydrogenatom, and R' represents a hydrogen atom, a methyl group, a hydroxyethylgroup or a phenyl group substituted by one or more chlorine atoms and/ormethyl groups. Included amongst numerous pyrazole compounds prepared anddisclosed by Southwick and Dhawan were5-amino-4-cyano-1-(2,4-dichlorophenyl)pyrazole and5-amino-4-cyano-1-(4-chloro-2-methylphenyl)pyrazole. This publicationcontains no suggestion that compounds of general formula I possess orwould be expected to possess herbicidal activity.

Apparently these pyrazole compounds did not lead (according to theauthors of the article) to useful therapeutic (viz. antimalarial)4,6-diaminopyrazolo[3,4-d]pyrimidines.

In Japanese Patent Application No. 29598/63 (applied for by TakedaChemical Industries Ltd: Publication No. 19958/65) there are disclosedpyrazole derivatives of the general formula: ##STR3## (wherein R₁represents a hydrogen atom or an unsubstituted phenyl group, R₂represents a hydrogen atom or a lower alkyl group, R₃ represents ahydrogen or halogen atom, or a nitro or cyano group and R₄ represents alower alkyl group, and an amino group or a lower alkoxy group) which areuseful as herbicides.

Our British Patent Application No. 8105778 (British Patent PublicationNo. 2070604A) discloses that when the substituent R₁ on the pyrazolering of compounds of general formula II is a phenyl radical carryingparticular substituents, R₂ represents a hydrogen atom, R₃ represents acyano or substituted carbamoyl radical, and R₄ represents an aminogroup, the compounds also have useful herbicidal activity and haveunexpectedly advantageous herbicidal properties in relation toparticular compounds disclosed in Japanese Patent Application No.29598/63 (Publication No. 19958/65-Derwent Basic No. G 3904), e.g. theclosely related compound 1-phenyl-4-cyano-5-aminopyrazole.

British Patent Application No. 8105778 accordingly provides, asherbicides, N-phenylpyrazole derivatives of the general formula:##STR4## wherein each of the symbols R⁵ and R⁶, which may be the same ordifferent, represents an alkyl or alkoxy radical containing from 1 to 4carbon atoms, a trifluoromethyl, trifluoromethoxy, nitro, cyano orprimary amino radical, or a fluorine, chlorine or bromine atom, each ofthe symbols R⁷, R⁸ and R⁹, which may be the same or different,represents a hydrogen atom, an alkyl or alkoxy radical containing from 1to 4 carbon atoms, a trifluoromethyl, trifluoromethoxy, nitrio, cyano orprimary amino radical or a fluorine, chlorine or bromine atom, or thesymbols R⁵, R⁷, R⁸ and R⁹ each represents a hydrogen atom and the symbolR⁶ represents a trifluoromethoxy or, preferably, a trifluoromethylradical, and the symbol R¹⁰ represents a cyano radical or substitutedcarbamoyl radical --CONHR¹¹ (wherein R¹¹ represents a methyl or ethylradical) and, when at least one of symbols R⁵, R⁶, R⁷, R⁸ and R⁹represents a primary amino radical, agriculturally acceptable acidaddition salts thereof.

The following compounds of general formula III are disclosed in BritishPatent Application No. 8105778 as being of particular interest asherbicides:

    ______________________________________                                        Compound                                                                      ______________________________________                                        A       5-amino-4-cyano-1-(2,3,4-trichlorophenyl)pyrazole                     B       5-amino-4-cyano-1-(2-nitro-4-trifluoromethyl-                                 phenyl)pyrazole                                                       C       5-amino-4-cyano-1-(2,4-dichlorophenyl)pyrazole                        D       5-amino-1-(2-bromo-3,4-dichlorophenyl)-4-                                     cyanopyrazole                                                         E       5-amino-4-cyano-1-(3,4-dichloro-2-methyl-                                     phenyl)pyrazole                                                       F       5-amino-1-(3-bromo-2,4-dichlorophenyl)-4-                                     cyanopyrazole                                                         G       5-amino-4-cyano-1-(2,4-dichloro-3-methyl-                                     phenyl)pyrazole                                                       H       5-amino-4-cyano-1-(2,4-dichloro-3-methoxy-                                    phenyl)pyrazole                                                       J       5-amino-4-cyano-1-(3-cyano-2,4-dichlorophenyl)-                               pyrazole                                                              K       5-amino-1-(4-bromo-2,3-dichlorophenyl)-4-                                     cyanopyrazole                                                         L       5-amino-4-cyano-1-(2,3-dichloro-4-methylphenyl)-                              pyrazole                                                              M       5-amino-4-cyano-1-(4-bromo-2-chloro-3-methyl-                                 phenyl)pyrazole                                                       N       5-amino-4-cyano-1-(2-chloro-3,4-dimethyl-                                     phenyl)pyrazole                                                       P       5-amino-4-cyano-1-(2-chloro-3-cyano-4-methyl-                                 phenyl)pyrazole                                                       Q       5-amino-1-(3-chloro-2,4-dibromophenyl)-4-                                     cyanopyrazole                                                         R       5-amino-1-(3-chloro-2,4-dimethylphenyl)-4-                                    cyanopyrazole                                                         S       5-amino-1-(2-bromo-4-chloro-3-methylphenyl)-4-                                cyanopyrazole                                                         T       5-amino-1-(4-chloro-2,3-dimethylphenyl)-4-                                    cyanopyrazole                                                         U       5-amino-1-(4-chloro-3-cyano-2-methylphenyl)-                                  4-cyanopyrazole                                                       V       5-amino-4-cyano-1-(2,4,5-trichlorophenyl)-                                    pyrazole                                                              W       5-amino-4-cyano-1-(2,4,6-trichlorophenyl)-                                    pyrazole                                                              X       5-amino-4-cyano-1-(2,3,4,5-tetrachlorophenyl)-                                pyrazole                                                              Y       5-amino-4-cyano-1-(2,3,4,6-tetrafluorophenyl)-                                pyrazole                                                              Z       5-amino-4-cyano-1-pentachlorophenylpyrazole                           AA      5-amino-4-cyano-1-pentafluorophenylpyrazole                           BB      5-amino-4-cyano-1-(4-trifluoromethylphenyl)-                                  pyrazole                                                              CC      5-amino-4-cyano-1-(3-chloro-2,4-difluorophenyl)-                              pyrazole                                                              DD      5-amino-4-N--methylcarbonamido-1-(2,3,4-trichloro-                            phenyl)pyrazole                                                       EE      5-amino-4-N--ethylcarbonamido-1-(2,3,4-trichloro-                             phenyl)pyrazole                                                       ______________________________________                                    

The letters of the alphabet A to H, J to N and P to EE are assigned tothe above compounds for identification and easy reference hereafter inthe present specification.

Particularly preferred compounds according to British Patent ApplicationNo. 8105778 are, referring to the identification by letters of thealphabet indicated above, Compound C, and more especially Compounds D toH, J to N and P to U and, in particular, Compound A.

European Patent Application No. 0 026 034 also discloses that Compound W[5-amino-4-cyano-1-(2,4,6-trichlorophenyl)pyrazole] possesses valuableherbicidal properties.

As a result of further extensive research and experimentation, it hasnow been found that when the substituent R₁ on the pyrazole ring ofcompounds of general formula II is a phenyl group substituted in the4-position by a trifluoromethyl group, in the 2-position by a chlorineor fluorine atom, and optionally in the 3-, 5- and 6-positions byfluorine or chlorine atoms as hereinafter more particularly described,these compounds unexpectedly possess outstandingly advantageousherbicidal activity in comparison with the herbicidal N-phenylpyrazolederivatives disclosed in British Patent Application No. 8105778 andother closely related compounds disclosed in the prior art.

The present invention accordingly provides, as herbicides, the newN-phenylpyrazole derivatives of the general formula: ##STR5## whereinR¹² represents a chlorine atom, R¹³ represents a hydrogen, fluorine orchlorine atom, R¹⁴ represents a hydrogen or fluorine atom and R¹⁵represents a hydrogen, fluorine or chlorine atom, with the proviso thatwhen R¹⁴ represents a fluorine atom, R¹⁵ represents a fluorine orchlorine atom, or R¹², R¹³ and R¹⁵ each represents a fluorine atom andR¹⁴ represents a hydrogen or fluorine atom. When R¹³ represents ahydrogen atom, R¹⁴ preferably represents a hydrogen atom.

Representative compounds of general formula IV according to the presentinvention include5-amino-1-(2-chloro-4-trifluoromethylphenyl)-4-cyanopyrazole (identifiedhereinafter as Compound No. 1),5-amino-4-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)pyrazole(identified hereinafter as Compound No. 2),5-amino-4-cyano-1-(2,3,6-trichloro-4-trifluoromethylphenyl)pyrazole(identified hereinafter as Compound No. 3) and5-amino-4-cyano-1-(2,3,5,6-tetrafluoro-4-trifluoromethylphenyl)pyrazole(identified hereinafter as Compound No. 4).

In experiments on herbicidal activity carried out on representativecompounds of general formula III disclosed in British Patent ApplicationNo. 8105778, the closely related compound1-phenyl-4-cyano-5-aminopyrazole specifically disclosed in JapanesePatent Application No. 29598/1963 (test Compound CC1) and the closelyrelated compound5-amino-4-cyano-1-(2,3,4-trichlorophenyl)-3-methylpyrazole (testCompound CC2), and representative compounds of general formula IV(Compounds Nos. 1, 2, 3 and 4), the following results have beenobtained:

EXPERIMENT 1 TEST METHODS (1) Weed Control Test

(a) General

The test compounds A to H, J to N and P to EE, CC1, CC2, No. 1, No. 2,No. 3 and No. 4 (as hereinbefore identified) were dissolved in acetone.Application was from a standard laboratory herbicide sprayer using aflat fan jet travelling at 1.6 m.p.h. (2.6 km/hour) and delivering theequivalent of 530 liters of spray fluid per hectare, the spray pressurebeing 2.81 kg/cm² (40 pounds/inch²). The solutions of test compounds Ato H, J, K, M, N and Q to EE, CC1 and CC2 were prepared by dissolving0.513 g of test compound in acetone and making up with acetone to 34 ml(1.5% w/v), equivalent to an application rate of 8 kg of test compoundper hectare. Solutions equivalent to 4, 2, 1, 0.5, 0.25 and 0.125kilogrammes per hectare (kg/ha) were prepared from these solutions byserial dilution with acetone, except for test compounds C, W, AA, BB,DD, EE and CC1 for which solutions equivalent to 8, 4, 2, 1 and 0.5kg/ha were prepared. The solutions of test compounds L and P weresimilarly prepared but using 0.128 g of test compound to give solutionsequivalent to application rates of 2, 1, 0.5, 0.25 and 0.125 kg/ha. Thesolutions of test compounds Nos. 1, 2 and 4 were similarly prepared butusing 0.128 g of test compound to give solutions equivalent toapplication rates of 2, 1, 0.5, 0.25, 0.125, 0.0625, 0.0312 and 0.0156kg/ha. The solutions of test compound No. 3 were similarly prepared butusing 0.064 g of test compound to give solutions equivalent toapplication rates of 1, 0.5, 0.25, 0.125, 0.0625, 0.0312 and 0.0156kg/ha.

(b) Weed Control: Pre-emergence application

Weed seeds were sown on the surface of John Innes No. 1 potting compost(7 parts by volume of sterilized loam, 3 parts by volume of peat and 2parts by volume of fine grit) in 9 cm diameter bitumenised paper pots.The quantities of seeds per pot were as follows:

    ______________________________________                                                         Approximate number                                           Weed species     Seeds/pot                                                    ______________________________________                                        (i) Broad leafed weeds                                                        Sinapis arvensis 30-40                                                        Polygonum lapathifolium                                                                        30-40                                                        Stellaria media  30-40                                                        (ii) Grass weeds                                                              Avena fatua      15-20                                                        Alopecurus myosuroides                                                                         30-40                                                        Echinochloa crus-galli                                                                         20-30                                                        ______________________________________                                    

The test compounds were applied to the uncovered seeds as described in(1) (a) above at dose rates of 0.125 to 8 kg/ha, except for testcompounds L and P, which were applied at dose rates of 0.125 to 2 kg/ha,for test compounds C, W, AA, BB, DD, EE and CC1 which were applied atdose rates of 0.5 to 8 kg/ha, for test compounds Nos. 1, 2 and 4 whichwere applied at dose rates of 0.0156 to 2 kg/ha, and test compound No. 3which was applied at dose rates of 0.0156 to 1 kg/ha, and the seeds werecovered with 25 ml of sharp sand after spraying. A single pot of eachweed species was allocated to each treatment, with unsprayed controlsand controls sprayed with acetone alone. After treatment, the pots werekept in the greenhouse and were watered overhead. Visual assessment ofweed control activity was made 19 to 28 days after spraying. The resultswere expressed as the minimum effective dose (MED) in kg/ha which gave90% reduction in growth or kill of the weeds in comparison with plantsin the control pots. The results obtained are presented below in TableI.

(c) Weed Control: Post-emergence application

Weed species were grown and then transplanted at the seedling stage intoJohn Innes No. 1 potting compost in 9 cm diameter bitumenised paperpots, except for Avena fatua, which was sown directly in the test potand not transplanted. The plants were then grown in the greenhouse untilready for spraying with the test compounds. The number of plants per potand the growth stage of the plant at spraying were as follows:

    ______________________________________                                                        Number of   Growth stages                                     Weed species    plants/pot  at spraying                                       ______________________________________                                        (i) Broad leafed weeds                                                        Polygonum lapathifolium                                                                       5           1-11/2 pairs of                                                               leaves                                            Stellaria media 5           4-6 leaves                                        Abutilon theophrasti                                                                          3           2 pairs of leaves                                 (ii) Grass weeds                                                              Avena fatua     10          1 leaf                                            Alopecurus myosuroides                                                                        5           11/2 leaves                                       Echinochloa crus-galli                                                                        5           1-2 leaves                                        ______________________________________                                    

The test compounds were applied to the plants as described in (1) (a)above at dose rates of from 0.125 to 8 kg/ha, except for test compoundsL and P which were applied at dose rates of 0.125 to 2 kg/ha, for testcompounds C, W, AA, BB, DD, EE and CC1 which were applied at dose ratesof 0.5 to 8 kg/ha, for test compounds Nos. 1, 2 and 4 which were appliedat dose rates of 0.0156 to 2 kg/ha, and test compound No. 3 which wasapplied at dose rates of 0.0156 to 1 kg/ha. A single pot of each weedspecies was allocated to each treatment, with unsprayed controls andcontrols sprayed with acetone alone. After spraying, the pots werewatered overhead, commencing 24 hours after spraying. Assessment of thecontrol of the growth of the weeds was made 19-28 days after spraying byrecording the number of plants which had been killed and the reductionin growth. The results were expressed as the minimum effective dose(MED) in kg/ha which gave 90% reduction in growth or kill of the weedsin comparison with the plants in the control pots. The results obtainedare presented below in Table II.

KEY TO WEED SPECIES

(a) GRASS WEEDS:

Am=Alopecurus myosuroides

Af=Avena fatua

Ec=Echinochloa crus-galli

(b) BROAD-LEAF WEEDS

Sm=Stellaria media

Pl=Polygonum lapathifolium

Sa=Sinapis arvensis

At=Abutilon theophrasti

                  TABLE I                                                         ______________________________________                                        Test    PRE-EMERGENCE MED (kg/ha)                                             Compound                                                                              Pl      Sa       Sm    Am    Af    Ec                                 ______________________________________                                        A       0.25    0.125    0.5-1 0.5   0.5-1 0.125-                                                                        0.25                               B       0.5-1   0.5      >8    2     2-4   1-2                                C       0.5-1   0.5-1    8     4     4     1                                  D       0.5-1   0.25-    4-8   2     4     1                                                  0.5                                                           E       1       1-2      2-4   2-4   2-4   0.5-1                              F       0.5-1   0.5-1    2     2-4   1-2   0.5-1                              G       0.25-   0.25-    0.5   1-2   1-2   0.25-                                      0.5     0.5                        0.5                                H       0.5-1   2        1     2     1-2   2                                  J       0.5     0.5-1    4-8   2     1-2   1                                  K       1       0.5      1-2   2-4   2-4   1                                  L       0.5     1        >>2   >2    >2    1-2                                M       1       0.5-1    >8    4     4     0.5-1                              N       0.125-  0.25     8     4     2-4   0.25-                                      0.25                               0.5                                P       1       >>2      NR    NR    NR    2                                  Q       4       4        4     4-8   4-8   4-8                                R       1-2     4-8      >8    2-4   2-4   1-2                                S       1-2     0.5-1    2-4   4     4     4                                  T       0.5-1   2-4      4-8   0.5-1 2-4   2-4                                U       2       4-8      4-8   2-4   >8    2                                  V       1       2        8     8     4-8   1                                  W       0.5-1   <0.5     2     2-4   0.5-1 0.5-1                              X       2       1-2      0.5   2-4   2-4   2                                  Y       0.5     1.0      4-8   2-4   2     0.5-1                              Z       2-4     1-2      >>8   2-4   4-8   1                                  AA      1-2     1.0      8     2-4   1-2   1                                  BB      1-2     4        4-8   2-4   4     1-2                                CC      1       4        >>8   4     4     1                                  DD      4       1        8     >>8   NR    >8                                 EE      NR      2-4      NR    NR    NR    >>8                                CC1     8       >>8      8     NR    NR    >>8                                CC2     NR      NR       NR    NR    NR    NR                                 No 1    0.0312- 0.0312-  0.5-1 0.25- 0.25  0.25                                       0.0625  0.0625         0.5                                            No 2    0.0156- <0.0156  0.0625-                                                                             0.25- 0.25- 0.125                                      0.0312           0.125 0.5   0.5                                      No 3    0.125-  0.0156-  0.0625                                                                              1.0   0.25- 0.5                                        0.25    0.0312               0.5                                      No 4    0.0156- 0.0156   0.25  0.5   0.0312-                                                                             0.125                                      0.0312                       0.0625                                   ______________________________________                                    

                  TABLE II                                                        ______________________________________                                        Test                                                                          Com-  POST-EMERGENCE MED (kg/ha)                                              pound At        Pl       Sm    Am    Af    Ec                                 ______________________________________                                        A     0.125     0.125    1-2   4-8   4-8   2-4                                B     0.125     0.5      >8    >>8   >8    8                                  C     <0.5      <0.5     >>8   >8    >8    4                                  D     0.125-    0.125-   2-4   >8    >>8   >8                                       0.25      0.25                                                          E     <0.125    <0.125   2     >>8   >8    8                                  F     0.125-    0.25-    0.5-1 NR    >>8   >8                                       0.25      0.5                                                           G     <0.125    0.25-    4-8   >>8   >8    4                                                  0.5                                                           H     0.25      0.125-   0.25  >8    8     1-2                                                0.25                                                          J     <0.125    <0.125   NR    >8    >8    1-2                                K     0.25-     0.125-   2     NR    >8    >8                                       0.5       0.25                                                          L     <0.125    0.25-    >2    >>2   >>2   2                                                  0.5                                                           M     0.125-    0.25-    >8    NR    >>8   >8                                       0.25      0.5                                                           N     0.125-    0.25-    NR    >>8   >>8   8                                        0.25      0.5                                                           P     0.125-    0.5-1    >>2   >>2   >>2   NR                                       0.25                                                                    Q     0.125-    0.25     4-8   >>8   >>8   >>8                                      0.25                                                                    R     0.125-    0.25-    NR    >>8   >>8   >8                                       0.25      0.5                                                           S     0.125-    0.25-    1-2   NR    >>8   >8                                       0.25      0.5                                                           T     0.5-1     0.5-1    NR    >>8   >8    >8                                 U     1-2       0.5-1    >>8   >>8   >>8   >8                                 V     0.25-     0.5      >>8   >>8   >>8   >8                                       0.5                                                                     W     <0.5      <0.5     >>8   >8    8     2-4                                X     0.5-1     0.5-1    2     NR    NR    >8                                 Y     0.125-    0.25-    >>8   8     4-8   2                                        0.25      0.5                                                           Z     0.5-1     1-2      NR    >8    NR    >8                                 AA    <0.5      <0.5     NR    8     4     2-4                                BB    1         0.5-1    NR    >>8   >> 8  4-8                                CC    2-4       2        NR    >>8   >8    4                                  DD    1-2       >8       NR    NR    NR    >>8                                EE    4-8       8        NR    NR    NR    >>8                                CC1   >>8       >>8      NR    >>8   >>8   NR                                 CC2   NR        NR       NR    NR    >>8   NR                                 No 1  <0.0156   0.0156-  0.25  >>2   >2    0.5-1                                              0.0312                                                        No 2  <0.0156   <0.0156  0.0156-                                                                             >2.0  2.0   0.5                                                         0.0312                                               No 3  0.0156-   0.0312-  0.0625                                                                              >>1.0 >>1.0 1.0                                      0.0312    0.0625                                                        No 4  <0.0156   <0.0156  0.0625                                                                              2.0   0.5-1 0.125                              ______________________________________                                    

The following symbols which appear in the above Tables have thefollowing meanings:

`>>` means much greater than

`>` means greater than

`<` means less than

`NR` means no reduction at any dose rate applied

EXPERIMENT 2 Comparision of the post-emergence activity of Compounds 1,2 and 4 with Compounds A against Galium aparine, Veronica persica andViola arvensis

The weed species Galium aparine, Veronica persica and Viola arvensis areresistant to the phenylurea-type herbicides isoproturon andchlorotoluron at the application rates of these two herbicides normallyused to control the growth of broad-leafed weeds in cereal crops. Thewidespread use of isoproturon and chlorotoluron, particularly in WesternEurope, has resulted in these three weed species becoming a particularlyimportant problem in weed control in winter cereals.

TEST METHOD

All weed species were grown in John Innes potting compost (7 parts byvolume of sterilized loam, 3 parts by volume of peat and 2 parts byvolume of fine grit). At the cotyledon growth-stage, the plants werepricked out into 9 cm. diameter bitumenized paper pots and subsequentlygrown on in these.

The number of plants per pot and the growth stage of the plants at thetime of application of the test compounds was as follows:

    ______________________________________                                                   Height   Number of  Number of plants                               Weed species                                                                             (cm)     leaves     per pot                                        ______________________________________                                        Galium aparine                                                                           4 to 9   3 to 5     2                                                                  (whorls)                                                  Veronica persica                                                                         2 to 4   5 to 6     3                                              Viola arvensis                                                                           2 to 3   3 to 4     3                                              ______________________________________                                    

Application of the test compounds was from a standard laboratoryherbicide sprayer using a flat fan jet travelling at 1.6. m.p.h. (2.6km/hour) and delivering the equivalent of 260 liters of spray fluid perhectare, the spray pressure being 2.1 kg/cm² (30 pounds/inch²). Thesolutions of Compound Nos. 1, 2 and 4 and Compound A were prepared bydissolving 0.154 g of test compound in acetone and making up with moreacetone to a volume of 40 ml, equivalent to an application rate of 1 kgof test compound per hectare. Solutions equivalent to 0.5, 0.25, 0.125,0.0625 and 0.0312 kg/ha were prepared from these solutions by serialdilution with acetone. Three replicate pots of each weed species wereallocated to each treatment, with unsprayed controls and controlssprayed with acetone alone. After spraying, the pots were maintained inthe greenhouse with overhead watering, commencing 24 hours afterspraying. Assessment of the control of the growth of the weeds was made28 days after spraying by recording the number of plants which had beenkilled. The results for the replicates were averaged and the meanresults were expressed as the dose rate of each test compound whichkilled 90% of the plants (ED₉₀ kg/ha). The results obtained arepresented below in Table III.

                  TABLE III                                                       ______________________________________                                                  ED.sub.90 kg/ha (mean of 3 replicates)                                          Galium      Veronica  Viola                                       Test Compound                                                                             aparine     persica   arvensis                                    ______________________________________                                        Compound No 0.29        0.11      0.09                                        Compound No 0.23        0.10      0.09                                        2                                                                             Compound No 0.09        0.09      0.08                                        4                                                                             Compound No 0.75        0.29      0.31                                        A                                                                             ______________________________________                                    

EXPERIMENT 3 Control of Galium aparine in winter wheat with CompoundsNos. 1 and 2 and Compound A TEST METHOD

Wettable powder formulations were prepared from:

(A)

Compound A--50% w/w

Arylan S90--3% w/w

Sopropon T.36--1% w/w

Belloid TD--5% w/w

Silica filler SAS132 (microfine silica) to 100% by weight

(B)

Compound No 1--20% w/w

Nekal BX--10% w/w

Sodium lignosulphate--3% w/w

Sopropon T.36--0.5% w/w

Silica filler SAS 132 to 100% by weight

(C)

Compound No 2--20% w/w

Nekal BX--10% w/w

Sodium lignosulphate--3% w/w

Sopropon T.36--0.5% w/w

Silica filler SAS 132 to 100% by weight

(Arylan S90 is sodium dodecylbenzenesulphonate; Sopropon T.36 is asodium polycarboxylate; Belloid TD is a condensate of sodium naphthalenesulphonate and formaldehyde; Nickal BX is a sodium alkyl naphthalenesulphonate).

The wettable powders were diluted with water and applied in 217.2 litersof spray fluid per hectare to 2.5×2.5 m plots containing emerged winterwheat (variety Avalon; growth stage: height 6 inches, 5 leaves unfolded,main shoot plus four tillers, pseudostem erect) and Galium aparine(growth stage: height 3 inches with 2 branches and 3 rosettes to height8 inches with 7 to 8 branches), using two replicates per treatment.

Compound A: 0.5, 1 and 2 kg/ha

Compound No 1: 0.125, 0.25, 0.5 and 1 kg/ha

Compound No 2: 0.125, 0.25, 0.5 and 1 kg/ha

Six days after spraying, the percentage control of Galium aparine andpercentage damage to the wheat in each treated plot was assessedvisually in comparison with unsprayed control plots. The mean percentagecontrol and damage figures for each pair of replicated plots was thencalculated and the results obtained are presented in the following TableIV. (The growth stage of the wheat at the time of assessment was: height8 inches, 6 main leaves, main shoot plus 4 tillers, first nodedetectable).

                  TABLE IV                                                        ______________________________________                                        Test    Application rate                                                                          % age control of                                                                           % age damage                                 Compound                                                                              (kg/ha)     Gallium aparine                                                                            to winter wheat                              ______________________________________                                        Compound                                                                              0.5         90           5                                            A       1           93           13                                                   2           98           18                                           Compound                                                                              0.125       70           0                                            No 1    0.25        83           0                                                    0.5         93           3                                                    1           100          5                                            Compound                                                                              0.125       90           0                                            No 2    0.25        95           0                                                    0.5         98           8                                                    1           98           5                                            ______________________________________                                    

The above experimental results clearly demonstrate the valuableherbicidal properties of the compounds of general formula IV and thesurprising and unexpected superiority in herbicidal activity, moreespecially by post-emergence application, possessed by the compounds ofgeneral formula IV in comparison with the compounds of general formulaIII, for example Compounds A, B, C, V, W, X, Y, Z, AA and BB, theclosely related compound 1-phenyl-4-cyano-5-aminopyrazole disclosed inJapanese Patent Application No. 29598/63 and a closely related compound5-amino-4-cyano-1-(2,3,4-trichlorophenyl)-3-methylpyrazole in whichsubstitution of the 3-position of the pyrazole ring by alkyl (methyl) astaught in Japanese Patent Application No. 29598/63 is combined withsubstitution in the 1-position of the pyrazole ring by a substitutedphenyl group (2,3,4-trichlorophenyl) found to confer high herbicidalactivity in the compounds of general formula III.

In particular, it is demonstrated in Experiment 1 that, bypost-emergence application, Compounds Nos. 1, 2, 3 and 4 are from atleast twice to more than eight times as active as Compound A incontrolling the growth of the important weed Polygonum lapathifolium,Compounds Nos. 1, 2, 3 and 4 are at least four times to more thansixteen times as active as Compound A and from at least thirtytwo tomore than sixty times as active as Compound W in controlling the growthof the important weed Stellaria media, Compounds Nos. 1, 2, 3 and 4 arefrom at least four to more than eight times as active as Compound A andCompounds Nos. 1, 3 and 4 are from at least eight to more than sixteentimes as active as Compound W in controlling the growth of Abutilontheophrasti and Compounds Nos. 1, 2, 3 and 4 are from at least twice tomore than eight times as active as Compounds A and W in controlling thegrowth of Echinochloa crus-galli. It is further demonstrated inExperiment 2 that Compound No. 1 is more than twice as active, CompoundNo. 2 is more than three times as active and Compound No. 4 is more thaneight times as active, as Compound A in controlling the growth of Galiumaparine, that Compounds Nos. 1, 2 and 4 are two to three times as activeas Compound A in controlling the growth of Veronica persica and thatCompounds Nos. 1, 2 and 4 are at least three times more active thanCompound A in controlling the growth of Viola arvensis, bypost-emergence application.

Experiment 3 demonstrates the high activity and selectivity of CompoundNo. 1 and, more especially, Compound No. 2 in controlling the growth ofthe very important weed species Galium aparine in a crop of winterwheat. Thus, Compound No. 1 is twice as active and Compound No. 2 is atleast four times as active as Compound A in controlling the growth ofGallium aparine, while Compounds Nos. 1 and 2 are both substantiallyless damaging to the winter wheat than Compound A.

Accordingly, a feature of the present invention is a method forcontrolling the growth of weeds (i.e. undesired vegetation) at a locuswhich comprises applying to the locus a herbicidally effective amount ofat least one N-phenylpyrazole derivative of general formula IV. For thispurpose, the N-phenylpyrazole derivatives are normally used in the formof herbicidal compositions (i.e. in association with compatible diluentsor carriers suitable for use in herbicidal compositions), for example ashereinafter described.

The compounds of general formula IV show herbicidal activity againstdicotyledonous (i.e. broad-leafed) and monocotyledonous (e.g. grass)weeds by pre- and/or, post-emergence application.

By the term "pre-emergence application" is meant application to the soilin which the weed seeds or seedlings are present before emergence of theweeds above the surface of the soil. By the term "post-emergenceapplication" is meant application to the aerial or exposed portions ofthe weeds which have emerged above the surface of the soil. For example,the compounds of general formula IV may be used to control the growth ofbroad-leafed weeds, for example, Abutilon theophrasti, Amaranthusretroflexus, Amsinckia intermedia, Anagallis arvensis, Atriplex patula,Brassica nigra, Capsella bursa-pastoris, Chenopodium album,Chrysanthemum segetum, Cirsium arvense, Datura stramonium, Desmodiumtortuosum, Emex australis, Euphorbia helioscopia, Fumaria officinalis,Galeopsis tetrahit, Galium aparine, Geranium dissectum, Ipomea purpurea,Lamium purpureum, Lapsana communis, Matricaria inodora, Monochoriavaginalis, Papaver rhoeas, Physalis longifolia, Plantago lanceolata,Polygonum spp., (e.g. Polygonum lapathifolium, Polygonum aviculare,Polygonum convolvulus and Polygonum persicaria), Portulaca oleracea,Raphanus raphanistrum, Rotala indica, Rumex obtusifolius, Saponariavaccaria, Scandix penten-veneris, Senecio vulgaris, Sesbania florida,Sida spinosa, Silene alba, Sinapis arvensis, Solanum nigrum, Sonchusarvensis, Spergula arvensis, Stellaria media, Thlaspi arvense, Tribulusterrestria, Urtica urens, Veronica hederifolia, Veronica persica, Violaarvensis and Xanthium strumarium, and grass weeds, for example,Alopecurus myosuroides, Apera spica-venti, Agrostis stolonifera, Avenafatua, Avena ludoviciana, Brachiaria spp., Bromus sterilis, Bromustectorum, Cenchrus spp., Cynodon dactylon, Digitaria sanquinalis,Echinochloa crus-galli, Eleusine indica, Setaria viridis and Sorghumhalepense and sedges, for example Cyperus esculentus, Cyperus iria andCyperus rotundus, and Eleocharis acicularis.

The amounts of compounds of general formula IV applied vary with thenature of the weeds, the compositions used, the time of application, theclimatic and edaphic conditions and (when used to control the growth ofweeds in crop-growing areas) the nature of the crops. When applied to acrop-growing area, the rate of application should be sufficient tocontrol the growth of weeds without causing substantial permanent damageto the crop. In general, taking these factors into account, applicationrates between 0.01 kg and 10 kg of active material per hectare give goodresults. However, it is to be understood that higher or lowerapplication rates may be used, depending upon the particular problem ofweed control encountered.

The compounds of general formula IV may be used to control selectivelythe growth of weeds, for example to control the growth of those specieshereinbefore mentioned, by pre- or post-emergence application in adirectional or non-directional fashion, e.g. by directional ornon-directional spraying, to a locus of weed infestation which is anarea used, or to be used, for growing crops, for example cereals, e.g.wheat, barley, oats, maize and rice, soya beans, field and dwarf beans,peas, lucerne, cotton, peanuts, flax, onions, carrots, cabbage, oilseedrape, sunflower, sugar beet, and permanent or sown grassland before orafter sowing of the crop or before or after emergence of the crop. Forthe selective control of weeds at a locus of weed infestation which isan area used, or to be used, for the growing of crops, e.g. the cropshereinbefore mentioned, application rates between 0.05 kg and 4.0 kg,and preferably between 0.1 kg and 2.0 kg, of active material per hectareare particularly suitable. More particularly, the compounds of generalformula IV may be used to control selectively the growth of broad leafedweeds, for example to control the growth of those broad leafed specieshereinbefore mentioned, by pre- or, more especially, post-emergenceapplication in a non-directional fashion, e.g. by non-directionalspraying, to an area used for growing cereal crops, e.g. wheat, barley,oats, maize and rice, before or after emergence of both the crop andweeds. The compounds of general formula IV are particularly useful forcontrolling selectively the growth of Galium aparine, Veronica persica,Veronica hederifolia, and Viola arvensis, by post-emergence applicationin a non-directional fashion, e.g. by non-directional spraying, to anarea used for growing cereals, e.g. wheat, barley and oats, afteremergence of both the crop and weeds.

For this purpose, i.e. the selective control of broad leafed weeds bypre- or post-emergence application to an area used for growing cerealcrops, application rates between 0.05 and 4.0 kg, and preferably between0.1 kg and 2.0 kg, of active material per hectare are particularlysuitable.

The high herbicidal activity of the compounds of general formula IV, andmore especially Compounds Nos. 1, 2 and 4, on Galium aparine, Veronicapersica and Viola arvensis renders them particularly suitable for use bypost-emergence application, in association with the phenylurea-typeherbicides isoproturon and chlorotoluron to control the growth of a widespectrum of weed species including, in addition to the threeaforementioned weed species, Matricaria inodora, Stellaria media,Galeopsis tetrahit, Avena fatua and Alopecurus myosuroides, inparticular in an emerged crop of winter wheat and barley. For thispurpose, application rates between 0.125 and 0.5 kg per hectare of theN-phenylpyrazole derivative(s) and application rates between 1.25 and2.5 kg per hectare of isoproturon or chlortoluron are generallysuitable.

The compounds of general formula IV may also be used to control thegrowth of weeds, especially those indicated above, by pre- orpost-emergence application in established orchards and othertree-growing areas, for example forests, woods and parks, andplantations, e.g. sugar cane, oil palm and rubber plantations. For thispurpose they may be applied in a directional or non-directional fashion(e.g. by directional or non-directional spraying) to the weeds or to thesoil in which they are expected to appear, before or after planting ofthe trees or plantations at application rates between 0.25 kg and 10.0kg, and preferably between 1.0 kg and 4.0 kg, of active material perhectare.

The compounds of general formula IV may also be used to control thegrowth of weeds, especially those indicated above, at loci which are notcrop-growing areas but in which the control of weeds is neverthelessdesirable. Examples of such non-crop-growing areas include airfields,industrial sites, railways, roadside verges, the verges of rivers,irrigation and other waterways, scrublands and fallow or uncultivatedland, in particular where it is desired to control the growth of weedsin order to reduce fire risks. When used for such purposes in which atotal herbicidal effect is frequently desired, the active compounds arenormally applied at dosage rates higher than those used in crop-growingareas as hereinbefore described. The precise dosage will depend upon thenature of the vegetation treated and the effect sought. Pre- orpost-emergence application, and preferably pre-emergence application, ina directional or non-directional fashion (e.g. by directional ornon-directional spraying) at application rates between 2.0 kg and 10.0kg, and preferably between 4.0 and 10.0 kg, of active material perhectare are particularly suitable for this purpose.

When used to control the growth of weeds by pre-emergence application,the compounds of general formula IV may be incorporated into the soil inwhich the weeds are expected to emerge. It will be appreciated that whenthe compounds of general formula IV are used to control the growth ofweeds by post-emergence application, i.e. by application to the aerialor exposed portions of emerged weeds, the compounds of general formulaIV will also normally come into contact with the soil and may also thenexercise a pre-emergence control on later-germinating weeds in the soil.

Where especially prolonged weed control is required, the application ofthe compounds of general formula IV may be repeated if required.

According to a further feature of the present invention, there areprovided compositions suitable for herbicidal use comprising one or moreof the N-phenylpyrazole derivatives of general formula IV in associationwith, and preferably homogeneously dispersed in, one or more compatibleherbicidally-acceptable diluents or carriers (i.e. diluents or carriersof the type generally accepted in the art as being suitable for use inherbicidal compositions and which are compatible with compounds ofgeneral formula IV). The term "homogeneously dispersed" is used toinclude compositions in which the compounds of general formula IV aredissolved in the other components. The term "herbicidal compositions" isused in a broad sense to include not only compositions which are readyfor use as herbicides but also concentrates which must be diluted beforeuse. Preferably, the compositions contain from 0.05 to 90% by weight ofone or more compounds of general formula IV.

The herbicidal compositions may contain both a diluent or carrier and asurface-active (e.g. wetting, dispersing, or emulsifying) agent.Surface-active agents which may be present in herbicidal compositions ofthe present invention may be of the ionic or non-ionic types, forexample sulphoricinoleates, quaternary ammonium derivatives, productsbased on condensates of ethylene oxide with nonyl- or octyl-phenols, orcarboxylic acid esters of anhydrosorbitols which have been renderedsoluble by etherification of the free hydroxy groups by condensationwith ethylene oxide, alkali and alkaline earth metal salts of sulphuricacid esters and sulphonic acids such as dinonyl- and dioctyl-sodiumsulphonosuccinates and alkali and alkaline earth metal salts of highmolecular weight sulphonic acid derivatives such as sodium and calciumlignosulphonates.

Suitably, herbicidal compositions according to the present invention maycomprise from 0.05% to 10% of surface-active agent but, if desired,herbicidal compositions according to the present invention may comprisehigher proportions of surface-active agent, for example up to 15% inliquid emulsifiable suspension concentrates and up to 25% in liquidwater soluble concentrates.

Examples of suitable solid diluents or carriers are aluminium silicate,talc, calcined magnesia, kieselguhr, tricalcium phosphate, powderedcork, adsorbent carbon black and clays such as kaolin and bentonite. Thesolid compositions (which may take the form of dusts, granules orwettable powders) are preferably prepared by grinding the compounds ofgeneral formula IV with solid diluents or by impregnating the soliddiluents or carriers with solutions of the compounds of general formulaIV in volatile solvents, evaporating the solvents and, if necessary,grinding the products so as to obtain powders. Granular formulations maybe prepared by adsorbing the compounds of general formula IV (dissolvedin volatile solvents) onto the solid diluents or carriers in granularform and evaporating the solvents, or by granulating compositions inpowder form obtained as described above. Solid herbicidal compositions,particularly wettable powders, may contain wetting or dispersing agent(for example of the types described above), which may also, when solid,serve as diluents or carriers.

Liquid compositions according to the invention may take the form ofaqueous, organic or aqueous-organic solutions, suspensions and emulsionswhich may incorporate a surface-active agent. Suitable liquid diluentsfor incorporation in the liquid compositions include water,acetophenone, cyclohexanone, isophorone, toluene, xylene and mineral,animal and vegetable oils (and mixtures of these diluents).Surface-active agents, which may be present in the liquid compositions,may be ionic or non-ionic (for example of the types described above) andmay, when liquid, also serve as diluents or carriers.

Wettable powders and liquid compositions in the form of concentrates maybe diluted with water or other suitable diluents, for example mineral orvegetable oils, particularly in the case of liquid concentrates in whichthe diluent or carrier is an oil, to give compositions ready for use.When desired, liquid compositions of the compound of general formula IVmay be used in the form of self-emulsifying concentrates containing theactive substances dissolved in the emulsifying agents or in solventscontaining emulsifying agents compatible with the active substances, thesimple addition of water to such concentrates producing compositionsready for use.

Liquid concentrates in which the diluent or carrier is an oil may beused without further dilution using the electrostatic spray technique.

Herbicidal compositions according to the present invention may alsocontain, if desired, conventional adjuvants such as adhesives,protective colloids, thickeners, penetrating agents, stabilisers,sequestering agents, anticaking agents, colouring agents and corrosioninhibitors. These adjuvants may also serve as carriers or diluents.

Preferred herbicidal compositions according to the present invention areaqueous suspension concentrates which comprise from 10 to 70% w/v of oneor more compounds of general formula IV, from 2 to 10% w/v ofsurface-active agent, from 0.1 to 5% w/v of thickener and from 15 to87.9% by volume of water; wettable powders which comprise from 10 to 90%w/w of one or more compounds of general formula IV, from 2 to 10% w/w ofsurface-active agent and from 10 to 88% w/w of solid diluent or carrier;liquid water soluble concentrates which comprise from 10 to 30% w/v ofone or more compounds of general formula IV, from 5 to 25% w/v ofsurface-active agent and from 45 to 85% by volume of water-misciblesolvent, e.g. dimethylformamide; liquid emulsifiable suspensionconcentrates which comprise from 10 to 70% w/v of one or more compoundsof general formula IV, from 5 to 15% w/v of surface-active agent, from0.1 to 5% w/v of thickener and from 10 to 84.9% by volume of organicsolvent; granules which comprise from 2 to 10% w/w of one or morecompounds of general formula IV, from 0.5 to 2% w/w of surface-activeagent and from 88 to 97.5% w/w of granular carrier, and emulsifiableconcentrates which comprise from 0.05 to 90% w/v, and preferably from 1to 60% w/v, of one or more compounds of general formula IV, from 0.01 to10% w/v, and preferably from 1 to 10% w/v, of surface-active agent andfrom 9.99 to 99.94%, and preferably from 39 to 98.99%, by volume oforganic solvent.

Herbicidal compositions according to the present invention may alsocomprise the compounds of general formula IV in association with, andpreferably homogeneously dispersed in, one or more other pesticidallyactive compounds and, if desired, one or more compatible pesticidallyacceptable diluents or carriers, surface-active agents and conventionaladjuvants as hereinbefore described. Examples of other pesticidallyactive compounds which may be included in, or used in conjunction with,the herbicidal compositions of the present invention include herbicides,for example to increase the range of weed species controlled, forexample alachlor[α-chloro-2,6-diethyl-N-(methoxymethyl)acetanilide],asulam[methyl(4-aminobenzenesulphonyl)carbamate], alloxydim Na[sodiumsalt of2-(1-allyloxyaminobutylidene)-5,5-dimethyl-4-methoxycarbonylcyclohexane-1,3-dione],atrazine[2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine],barban[4-chlorobut-2-ynyl N-(3-chlorophenyl)carbamate],benzoylprop-ethyl[ethylN-benzoyl-N-(3,4-dichlorophenyl-2-aminopropionate],bromoxynil[3,5-dibromo-4-hydroxybenzonitrile],butachlor[N-(butoxymethyl)-α-chloro-2,6-diethylacetanilide],butylate[S-ethyl N,N-diisobutyl(thiocarbamate)],carbetamide[D-N-ethyl-2-(phenylcarbamoyloxy)propionamide],chlorfenprop-methyl[methyl 2-chloro-3-(4-chlorophenyl)propionate],chloropropham[isopropyl N-(3-chlorophenyl)carbamate],chlortoluron[N'-(3-chloro-4-methylphenyl)-N,N-dimethylurea],cyanazine[2-chloro-4-(1-cyano-1-methylethylamino)-6-ethylamino-1,3,5-triazine],cycloate[N'-cyclohexyl-N-ethyl-S-ethyl(thiocarbamate)],2,4-D[2,4-dichlorophenoxyacetic acid], dalapon[2,2-dichloropropionicacid], 2,4-DB[4-(2,4-dichlorophenoxy)butyric acid],desmedipham[3-(ethoxycarbonylamino)phenyl N-phenyl-carbamate],diallate[S-2,3-dichloroallyl-N,N-di-isopropyl(thiocarbamate)],dicamba[3,6-dichloro-2-methoxybenzoic acid],dichlorprop[(±)-2-(2,4-dichlorophenoxy)propionic acid],difenzoquat[1,2-dimethyl-3,5-diphenyl-pyrazolium salts],dimefuron{4-[2-chloro-4-(3,3-dimethylureido)phenyl]-2-t-butyl-1,3,4-oxadiazolin-5-one},dinitramine[N¹,N¹-diethyl-2,6-dinitro-4-trifluoromethyl-m-phenylenediamine],diuron[N'-(3,4-dichlorophenyl)-N,N-dimethylurea], EPTC[S-ethylN,N-dipropyl(thiocarbamate)],ethofumesate[2-ethoxy-2,3-dihydro-3,3-dimethylbenzofuran-5-ylmethylsulphonate],flampropisopropyl[isopropyl(±)-2-(N-benzoyl-3-chloro-4-fluoroanilino)propionate],flampropmethyl[methyl(±)-2-(N-benzoyl-3-chloro-4-fluoroanilino)propionate],fluometuron[N'-(3-trifluoromethylphenyl)-N,N-dimethylurea],ioxynil[4-hydroxy-3,5-di-iodobenzonitrile],isoproturon[N'-(4-isopropylphenyl)-N,N-dimethylurea],linuron[N-(3,4-dichlorophenyl)-N-methoxy-N-methylurea],MCPA[4-chloro-2-methylphenoxyacetic acid],MCPB[4-(4-chloro-2-methylphenoxy)butyric acid],mecoprop[(±)-2-(4-chloro-2-methylphenoxy)propionic acid],metamitron[4-amino-3-methyl-6-phenyl-1,2,4-triazin-5(4H)-one],methabenzthiazuron[N-(benzothiazol-2-yl)-N,N'-dimethylurea],metribuzin[4-amino-6-t-butyl-3-(methylthio)-1,2,4-triazin-5(4H)-one],molinate[S-ethyl N,N-hexamethylene(thiocarbamate)],oxadiazon[3-(2,4-dichloro-5-isopropoxyphenyl)-5-t-butyl-1,3,4-oxadiazolin-2-one],paraquat[1,1'-dimethyl-4,4'-bipyridylium salts], pebulate[S-propylN-butyl-N-ethyl(thiocarbamate)],phenmedipham[3-(methoxycarbonylamino)phenylN-(3-methylphenyl)carbamate],prometryne[4,6-bisisopropylamino-2-methylthio-1,3,5-triazine],propachlor[α-chloro-N-isopropylacetanilide],propanil[N-(3,4-dichlorophenyl)propionamide], propham[isopropylN-phenylcarbamate],pyrazone[5-amino-4-chloro-2-phenylpyridazin-3(2H)-one],simazine[2-chloro-4,6-bisethylamino-1,3,5-triazine], TCA(trichloroacetic acid),thiobencarb[S-(4-chlorobenzyl)-N,N-diethylthiolcarbamate],tri-allate[S-2,3,3-trichloroallyl N,N-di-isopropyl(thiocarbamate)] andtrifluralin[2,6-dinitro-N,N-dipropyl-4-trifluoromethylaniline];insecticides, e.g. carbaryl[naphth-1-yl N-methylcarbamate]; syntheticpyrethroids, e.g. permethrin and cypermethrin; and fungicides, e.g.2,6-dimethyl-4-tridecyl-morpholine, methylN-(1-butyl-carbamoyl-benzimidazol-2-yl)carbamate,1,2-bis(3-methoxycarbonyl-2-thioureido)benzene, isopropyl1-carbamoyl-3-(3,5-dichlorophenyl)hydantoin and1-(4-chloro-phenoxy)-3,3-dimethyl-1-(1,2,4-triazol-1-yl)butan-2-one.Other biologically active materials which may be included in, or used inconjunction with, the herbicidal compositions of the present inventionare plant growth regulators, e.g. succinamic acid,(2-chloroethyl)trimethylammonium chloride and 2-chloroethane-phosphoricacid; or fertilizers, e.g. containing nitrogen, potassium and phosphorusand trace elements known to be essential to successful plant life, e.g.iron, magnesium, zinc, manganese, cobalt and copper.

Herbicidal compositions according to the present invention whichcomprise the compounds of general formula IV, and more especiallyCompounds Nos. 1, 2 and 4 in association with, and preferablyhomogeneously dispersed in, isoproturon and chlortoluron and, ifdesired, one or more compatible pesticidally acceptable diluents orcarriers, surface-active agents and conventional adjuvants, moreespecially in the ratio 1:2.5 to 1:20 by weight of N-phenylpyrazolederivative(s) to isoproturon or chlortoluron, are particularly suitablefor use by post-emergence application to control the growth of Galiumaparine, Veronica persica, Veronica hederifolia, Viola arvensis,Matricaria inodora, Stellaria media, Galeopsis tetrahit, Avena fatua andAlopecurus myosuroides, in particular in an emerged crop of winter wheatand barley.

Pesticidally active compounds and other biologically active materialswhich may be included in, or used in conjunction with, the herbicidalcompositions of the present invention, for example those hereinbeforementioned, and which are acids, may, if desired, be utilized in the formof conventional derivatives, for example alkali metal and amine saltsand esters.

According to a further feature of the present invention there isprovided an article of manufacture comprising at least one of theN-phenyl-pyrazole derivatives of general formula IV or, as is preferred,a herbicidal composition as hereinbefore described, and preferably aherbicidal concentrate which must be diluted before use, comprising atleast one of the N-phenylpyrazole derivatives of general formula IVwithin a container for the aforesaid derivative or derivatives ofgeneral formula IV, or a said herbicidal composition, and instructionsphysically associated with the aforesaid container setting out themanner in which the aforesaid derivative or derivatives of generalformula IV or herbicidal composition contained therein is to be used tocontrol the growth of weeds. The containers will normally be of thetypes conventionally used for the storage of chemical substances whichare solid at normal ambient temperatures and herbicidal compositionsparticularly in the form of concentrates, for example cans and drums ofmetal, which may be internally-lacquered, and plastics materials,bottles of glass and plastics materials and, when the contents of thecontainer is a solid, for example granular, herbicidal compositions,boxes, for example of cardboard, plastics maerials and metal, or sacks.The containers will normally be of sufficient capacity to containamounts of the N-phenylpyrazole derivative or herbicidal compositionssufficient to treat at least one acre of ground to control the growth ofweeds therein but will not exceed a size which is convenient forconventional methods of handling. The instructions will be physicallyassociated with the container, for example by being printed directlythereon or on a label or tag affixed thereto. The directions willnormally indicate that the contents of the container, after dilution ifnecessary, are to be applied to control the growth of weeds at rates ofapplication between 0.01 kg and 10 kg of active material per hectare inthe manner and for the purposes hereinbefore described.

The following Examples illustrate herbicidal compositions according tothe present invention.

EXAMPLE 1

5-Amino-4-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)pyrazole wasformulated as a water soluble concentrate containing5-amino-4-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)-pyrazole--10%w/v (weight/volume)

Ethylan KEO (nonylphenyl/ethylene oxide condensate containing 9-10 molesof ethylene oxide per mol of phenol)--10% w/v

Dimethylformamide to 100% by volume,

by dissolving the Ethylan KEO in a portion of dimethylformamide and thenadding the active ingredient with heating and stirring until dissolved.The resulting solution was then made up to 100% by volume by adding therest of the dimethylformamide.

5 Liters of the above formulation may be dissolved in 200 liters ofwater and sprayed post-emergence onto 1 hectare of an emerged crop ofspring-sown wheat to control Amaranthus retroflexus, Setaria viridis,Polygonum lapathifolium, Abutilon theophrasti and Solanum nigrum.

The 5-amino-4-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)pyrazolemay, if desired, be replaced in the above water soluble concentrate byany other compound of general formula IV.

EXAMPLE 2

A wettable powder was formed from:

5-amino-4-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)pyrazole--50%w/w (weight/weight)

Ethylan BCP (a nonylphenol/ethylene oxide condensate containing 9 molesof ethylene oxide per mol of phenol)--5% w/w

Aerosil (silicon dioxide of microfine particle size)--5% w/w

Celite PF (synthetic magnesium silicate carrier)--40% w/w

by adsorbing the Ethylan BCP onto the Aerosil, mixing with the otheringredients and grinding the mixture in a hammermill to give a wettablepowder which may be diluted with water and applied at an applicationrate of 1.0 kg of wettable powder in 300 liters of spray fluid perhectare to control the growth of Galium aparine, Veronica persica, Violaarvensis, Galeopsis tetrahit and Stellaria media by post-emergenceapplication in an emerged crop of winter wheat.

Similar wettable powders may be prepared as described above by replacingthe 5-amino-4-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)pyrazole byother compounds of general formula IV.

EXAMPLE 3

An aqueous suspension concentrate was formed from:

5-amino-4-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)pyrazole--50%w/v

Ethylan BCP--1.0% w/v

Sopropon T36 (sodium salt of polycarboxylic acid)--0.2% w/v

Ethylene glycol--5% w/v

Rhodigel 23 (polysaccharide xanthan gum thickener)--0.15% w/v

distilled water to 100% by volume

by intimately mixing the ingredients and grinding in a ball-mill for 24hours. The concentrate thus obtained may be dispersed in water andapplied at an application rate of 1.0 kg of aqueous suspensionconcentrate in 300 liters of spray fluid per hectare to control thegrowth of Galium aparine, Veronica persica, Viola arvensis, Stellariamedia and Galeopsis tetrahit by post-emergence application in an emergedcrop of winter barley.

Similar aqueous suspension concentrates may be prepared as describedabove by replacing the5-amino-4-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)pyrazole byother compounds of general formula IV.

EXAMPLE 4

An emulsifiable suspension concentrate was formed from:

5-amino-4-cyano-1-(2-chloro-4-trifluoromethylphenyl)pyrazole--50% w/v

Ethylan TU (a nonyl phenol/ethylene oxide condensate containing 10 molesof ethylene oxide per mol of phenol)--10% w/v

Bentone 38 (an organic derivative of special magnesium montmorillonitethickener)--0.5% w/v

Aromasol H (an aromatic solvent consisting predominantly of isomerictrimethylbenzenes)--to 100% by volume

by intimately mixing the ingredients and grinding in a ball-mill for 24hours. The emulsifiable suspension concentrate thus obtained may bediluted with water and applied at an application rate of 2.0 kg ofemulsifiable suspension concentrate in 100 liters of spray fluid perhectare to control the growth of Setaria viridis, Polygonum convolvulus,and Chenopodium album by post-emergence application in an emerged cropof spring-sown wheat.

Similar emulsifiable suspension concentrates may be prepared asdescribed above by replacing the5-amino-4-cyano-1-(2-chloro-4-trifluoromethylphenyl)pyrazole by othercompounds of general formula IV.

EXAMPLE 5

Granules were formed from:

5-amino-4-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)pyrazole--5% w/w

Ethylan BCP--1% w/w

Oleic acid--1% w/w

Aromasol H--12% w/w

30/60 Attapulgite granules (sorptive silica clay)--81% w/w

by mixing the phenylpyrazole, Ethylan BCP, oleic acid and Aromasol H andspraying the mixture onto the Attapulgite granules. The granules thusobtained may be applied at an application rate of 20 kg of granules perhectare to control the growth of Echinochloa crus-galli, Eleocharisacicularis and Monochoria vaginalis by pre-emergence application orapplication to seedling weeds in a crop of transplanted paddy rice.

Similar granules may be prepared as described above by replacing the5-amino-4-cyano-1-(2,6-dichloro-4-trifuoromethylphenyl)pyrazole by othercompounds of general formula IV.

EXAMPLE 6

A water soluble concentrate was formed from:

5-amino-4-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)pyrazole--10%w/v

Ethylan KEO--10% w/v

Dimethylformamide--to 100% by volume

by dissolving the Ethylan KEO in a portion of dimethylformamide and thenadding the pyrazole derivative with heating and stirring untildissolved. The resulting solution was then made up to 100% by volumewith dimethylformamide by adding the rest of the dimethylformamide. Thewater soluble concentrate thus obtained may be diluted with water andapplied at an application rate of 10 liters of water soluble concentratein 200 to 2000 liters of spray fluid per hectare to control the growthof Galium aparine, Veronica persica, Viola arvensis and Galeopsistetrahit by post-emergence application in an emerged crop of winterwheat at the tillering growth stage.

EXAMPLE 7

A wettable powder was formed from:

5-amino-4-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)pyrazole--90%w/w

Arylan S (sodium dodecyl benzene sulphonate)--2% w/w

Darvan No. 2 (sodium lignosulphate)--5% w/w

Celite PF--3% w/w

by mixing the ingredients and grinding the mixture in a hammer-mill togive a wettable powder which may be diluted with water and applied at anapplication rate of 1.0 kg of wettable powder in 300 liters of sprayfluid per hectare to control the growth of Galium aparine, Veronicapersica, Viola arvensis and Galeopsis tetrahit by post-emergenceapplication in an emerged crop of winter wheat.

Similar wettable powders may be prepared as described above by replacingthe 5-amino-4-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)pyrazole byother compounds of general formula IV.

EXAMPLE 8

A wettable powder containing 50% w/w of5-amino-4-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)pyrazole,prepared as hereinbefore described in Example 2, may be diluted withwater and applied at an application rate of 0.1 kg of wettable powder in300 liters of spray fluid per hectare to control the growth of Abutilontheophrasti and Polygonum convolvulus by post-emergence application atthe early seedling growth stage of these weeds in a crop of springwheat.

EXAMPLE 9

A wettable powder containing 50% w/w of5-amino-4-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)pyrazole,prepared as described in Example 2, may be diluted with water andapplied at an application rate of 20 kg of wettable powder in 600 litersof spray fluid per hectare to produce a total herbicidal effect onvegetation at a locus which is not a crop-growing area.

EXAMPLE 10

An emulsifiable concentrate was formed from:

5-amino-4-cyano-1-(2,3,5,6-tetrafluoro-4-trifluoromethylphenyl)pyrazole--20%w/v

Soprophor BSU (condensate of tristyrylphenol and ethylene oxide,containing 18 moles of ethylene oxide)--3.75 w/v

Arylan CA (70% solution of calcium dodecyl benzene sulphonate)--3.75 w/v

Isophorone--60% w/v

Aromasol H--to 100% by volume,

by dissolving the Soprophor BSU and Arylan CA in a portion of theisophorone and then adding the phenylpyrazole, with heating, andstirring until dissolved. The remaining isophorone was then added andthe soluton was made up to 100% by volume by adding the Aromasol H. Theemulsifiable concentrate thus obtained may be diluted with water andapplied at an application rate of 1 liter of emulsifiable concentrate in200 liters of spray fluid per acre to control the growth of Galiumaparine, Stellaria media, Veronica persica, Veronica hederifolia andViola arvensis by post-emergence application in an emerged crop ofwinter wheat.

EXAMPLE 11

An aqueous suspension concentrate containing 50% w/v of5-amino-4-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)pyrazoleprepared as described in Example 3 (1.25 liters) and a commerciallyavailable 50% w/v aqueous suspension concentrate of isoproturon (15liters) were mixed with water in the spray tank and applied at anapplication rate of 0.125 kg of the N-phenylpyrazole derivative and 1.5kg of isoproturon in 200 liters of spray fluid per hectare to an emergedcrop of winter wheat to control the growth of Alopecurus myosuroides,Stellaria media, Matricaria inodora, Gallium aparine, Veronica persicaand Viola arvensis by post-emergence application.

According to a feature of the present invention, the N-phenylpyrazolederivatives of general formula IV wherein R¹², R¹³, R¹⁴ and R¹⁵ are ashereinbefore defined, are prepared by the process which comprises thecyclisation of a compound of the general formula: ##STR6## wherein thevarious symbols are as hereinbefore defined. Cyclisation may be effectedin the presence of an inert organic solvent, for example an alkanolcontaining from 1 to 4 carbon atoms (e.g. ethanol), acetic acid orethoxyethanol, at a temperature of from ambient temperature up to thereflux temperature of the reaction mixture.

Compounds of general formula V may be prepared by the reaction of acompound of the general formula: ##STR7## (wherein the various symbolsare as hereinbefore defined) or an acid addition salt thereof (e.g. thehydrochloride) with a compound of the general formula: ##STR8## whereinR¹⁶ represents a straight- or branched-chain alkyl radical containingfrom 1 to 4 carbon atoms, preferably ethyl.

The reaction of a compound of general formula VI with a compound ofgeneral formula VII may be effected in the presence of an inert organicsolvent, for example an alkanol containing from 1 to 4 carbon atoms(e.g. ethanol), acetic acid or ethoxyethanol and at a temperature offrom ambient temperature to the reflux temperature of the reactionmixture and optionally in the presence of an alkali metal (e.g. sodiumor potassium) acetate, carbonate or bicarbonate. When an acid additionsalt of the compound of general formula VI is used, the reaction withthe compound of general formula VII is effected in the presence of analkali metal (e.g. sodium or potassium) acetate, carbonate orbicarbonate.

N-Phenylpyrazole derivatives of general formula IV wherein R¹², R¹³, R¹⁴and R¹⁵ are as hereinbefore defined, may, according to another featureof the present invention, be prepared by reaction of a compound ofgeneral formula VI with a compound of general formula VII ashereinbefore described without isolation of an intermediate compound ofgeneral formula V from the reaction mixture. When the reaction of acompound of general formula VI with a compound of general formula VII iseffected in acetic acid, in the absence or presence of an alkali metal(e.g. sodium or potassium) acetate, the intermediate compound of formulaV may separate from the reaction mixture, depending upon the solubilityof the intermediate compound of general formula V in the reactionmedium, and may, if desired, be isolated before being cyclised ashereinbefore described to a compound of general formula IV, preferablyby heating in an inert organic solvent (e.g. ethoxyethanol) at thereflux temperature of the reaction mixture.

Isolated compounds of general formula V exhibit herbicidal activitiessimilar to those of the corresponding N-phenylpyrazole derivatives ofgeneral formula IV into which they may be cyclised, and it is believedthat the herbicidal activity of compounds of general formula V resultsfrom their cyclisation to compounds of general formula IV.

Compounds of general formula VI and VII may be prepared by methods knownper se. By the term "methods known per se" as used in the presentspecification is meant methods heretofore used or described in thechemical literature.

The following Examples and Reference Examples illustrate the preparationof compounds of general formula IV.

EXAMPLE 12

Ethoxymethylenemalononitrile [1.84 g; described by Huber, J. Amer. Chem.Soc., 65, 2224 (1943)] and 2,6-dichloro-4-trifluoromethylphenylhydrazine(3.7 g) were added to a magnetically-stirred solution of sodium acetate(0.6 g) in glacial acetic acid (15 ml) at laboratory temperature. Afterstirring for 15 minutes, a colourless solid precipitated from the clearbrown solution obtained and stirring was continued for a further 15minutes. The mixture was then filtered. The solid obtained was washedsuccessively with acetic acid, water, aqueous sodium bicarbonatesolution and water, to give2,6-dichloro-4-trifluoromethylphenylhydrazinomethylenemalononitrile (3.4g), m.p. 153°-154° C., in the form of colourless crystals.

The 2,6-dichloro-4-trifluoromethylphenylhydrazinomethylenemalononitrilethus obtained was then heated at reflux for 45 minutes in ethoxyethanol(15 ml). The hot solution was filtered and the filtrate was cooled,diluted with water (5 ml), and filtered, to give5-amino-4-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)pyrazole (2.5g), m.p. 165°-167° C., in the form of off-white crystals.

By proceeding in a similar manner, but replacing the2,6-dichloro-4-trifluoromethylphenylhydrazine by the hereinafterindicated appropriately substituted phenylhydrazine, there wereprepared: 5-Amino-1-(2-chloro-4-trifluoromethylphenyl)-4-cyanopyrazole,m.p. 185°-187° C., after crystallisation from toluene, in the form offawn-coloured crystals, from 2-chloro-4-trifluoromethylphenylhydrazine,via 2-chloro-4-trifluoromethylphenylhydrazinomethylenemalononitrile, inthe form of a brown powder, m.p. 138°-143° C.

5-Amino-4-cyano-1-(2,3,5,6-tetrafluoro-4-trifluoromethylphenyl)pyrazole,m.p. 122°-122.5° C., after crystallisation from toluene, in the form ofoff-white crystals, from2,3,5,6-tetrafluoro-4-trifluoromethylphenylhydrazine (prepared asdescribed by Alsop et al, J. Chem. Soc. 1962, 1801), via2,3,5,6-tetrafluorophenyl-4-trifluoromethylphenylhydrazinomethylenemalononitrile,m.p. 90°-93° C., in the form of a pale yellow solid.

EXAMPLE 13

2,3,6-Trichloro-4-trifluoromethylphenylhydrazine (10.1 g) was added inone portion to a solution of ethoxymethylenemalononitrile (4.40 g) andanhydrous sodium acetate (1.47 g) in glacial acetic acid (34 ml) stirredat laboratory temperature. After stirring at laboratory temperature for5 minutes, a fine precipitate formed and stirring at laboratorytemperature was continued for 2 hours. The reaction mixture was thenallowed to stand overnight at laboratory temperature and filtered. Thesolid precipitate was washed successively with a small quantity ofglacial acetic acid, saturated aqueous sodium bicarbonate solution andwater, to give2,3,6-trichloro-4-trifluoromethylphenylhydrazinomethylenemalononitrile(9.6 g), m.p. 169°-170° C., in the form of a fawn-coloured powder.

The2,3,6-trichloro-4-trifluoromethylphenylhydrazinomethylenemalononitrilethus obtained was heated at reflux for 1 hour in ethoxyethanol (50 ml).The hot solution was filtered and the filtrate was cooled, diluted withwater (70 ml) and the solid precipitate was filtered off to give5-amino-4-cyano-1-(2,3,6-trichloro-4-trifluoromethylphenyl)pyrazole(6.36 g), m.p. 186°-187° C., after crystallisation from toluene (25 ml),in the form of a buff-coloured crystalline solid.

REFERENCE EXAMPLE 1

Phenylhydrazines used as starting materials in Examples 12 and 13 wereprepared as follows:

2,6-Dichloro-4-trifluoromethylphenylaniline (4.3 g) (described in U.S.Pat. No. 3,850,955) was dissolved, with stirring, in glacial acetic acid(23 ml). A solution of sodium nitrite (1.5 g) in concentrated sulphuricacid (11 ml) was then added at 55°-60° C. The solution thus obtained wascooled to 0°-5° C. and a solution of stannous chloride (16.4 g) inconcentrated hydrochloric acid (14 ml) was added with vigorous stirring.A cream-coloured solid precipitated. The mixture was filtered and thesolid obtained was added to a mixture of aqueous ammonium hydroxidesolution and ice. The mixture thus obtained was extracted with diethylether (6×500 ml) and the combined ethereal extracts were dried oversodium sulphate, filtered and evaporated to dryness to give2,6-dichloro-4-trifluoromethylphenylhydrazine (3.7 g), m.p. 54°-56° C.,in the form of a colourless crystalline solid.

By proceeding in a similar manner, but replacing the2,6-dichloro-4-trifluoromethylaniline by2-chloro-4-trifluoromethylaniline (described in U.S. Pat. No.3,850,995), there was prepared2-chloro-4-trifluoromethylphenylhydrazine, m.p. 38°-39° C., in the formof a colourless solid.

By proceeding in a similar manner, but replacing the2,6-dichloro-4-trifluoromethylaniline by2,3,6-trichloro-4-trifluoromethylaniline, there was replaced2,3,6-trichloro-4-trifluoromethylphenylhydrazine, m.p. 72°-74° C., inthe form of a white solid.

REFERENCE EXAMPLE 2

2,3,6-Trichloro-4-trifluoromethylaniline, used as a starting material inReference Example 1, was prepared as follows:

A mixture of 3-chloro-4-trifluoromethylaniline [20 g; described inBritish Patent Specification No. 459890] and hydrochloric acid (d: 1.18;12 ml) was suspended in water (600 ml). Chlorine gas (from 13 ml ofliquid chlorine) was then passed into the stirred suspension withheating at reflux. On completion of the addition of chlorine gas,stirring was continued for a further 15 minutes. After cooling, thesolution thus obtained was extracted with dichloromethane (3×250 ml).The combined organic extracts were washed with water, saturated aqueoussolid bicarbonate solution and water, dried over anhydrous sodiumsulphate and evaporated. The red oil thus obtained was distilled (bp143°-147° C./20 mmHg) to give an orange oil which crystallized onstanding to give 2,3,6-trichloro-4-trifluoromethylaniline (12.26 g),m.p. 37°-39° C., in the form of an orange solid.

We claim:
 1. Compounds of the general formula: ##STR9## wherein R¹²represents a chlorine atom, R¹³ represents a hydrogen, fluorine orchlorine atom, R¹⁴ represents a hydrogen or fluorine atom and R¹⁵represents a hydrogen, fluorine or chlorine atom, with the proviso thatwhen R¹⁴ represents a fluorine atom, R¹⁵ represents a fluorine orchlorine atom, or R¹², R¹³ and R¹⁵ each represent a fluorine atom andR¹⁴ represents a hydrogen or fluorine atom.